The present invention relates to non-woven webs and, more particularly, to antimicrobially active, non-woven webs, to wet wipers containing such a web, and to a method of making the web.
Wet wiper products, including those utilizing non-woven and air-laid webs, require antimicrobial properties to destroy or inhibit the growth of various microorganisms, bacteria, yeasts, and molds. Presently, there are at least four methods of treating the fabric of the wet wiper product to obtain some type of antimicrobial protection--sterilization; pore size control, such as Bacterial Filtration Efficiency (BFE); chemical surface treatment; and overall chemical protection. All of these methods have demonstrated inherent deficiencies for wet wiper products.
Sterilization may be achieved by sterilizing the raw materials going into the make-up of the product and/or sterilizing the final packaged product. Sterilization is an excellent technique for killing the microorganisms present to provide a microbiologically clean product for the intended use. However, in the case of wet wipers, sterilization as an antimicrobial technique is limited because once the product package has been opened to dispense the wipers, the sterilization is voided and any remaining wipers are exposed to and therefore subject to microbiological growth. As a result, the product is rendered both useless and potentially harmful.
Therefore, sterilization is viable only for single use packages of wet wipers. Nevertheless, due to shelf life and package integrity concerns, all single use wet wipers packages commercially available still rely on additional chemical protection for good microbiological control.
Fabric pore size control by BFE can be used to control the passage of microorganisms from one side or surface of the fabric through the fabric to the other side or surface. Pore size control as a method of microbiological transport control is generally used only with a dry fabric and is found most frequently in the medical industry in such products as CSR wraps and face masks. This method of microorganism transport control is ineffective for use in a wet wiper, because any microorganisms present can pass entirely around the fabric in the liquid or lotion phase of the product.
Antimicrobial surface treatment of a fabric may also be beneficial in the dry mode of usage, where, along with the pore size control by BFE, microorganisms are either filtered out and/or killed upon contact with the surface of the fabric. However, again in the case of wet wipers, surface treatment of the fabric has been shown to be insufficient to obtain the necessary microbiological control. The liquid or lotion phase of the wet wiper product penetrates into the interstices of the fabric to carry the microorganisms past the treated surface into the interstices of the fabric, where they may then grow and multiply.
Virtually the only method of antimicrobial control and protection presently used in wet wiper products is that which is achieved by a chemical permeation of preservative agents throughout the wet wiper product. This permeation may be achieved by padding the wiper fabric during its manufacture and/or by incorporating the chemicals in the liquid or lotion phase of the wiper product.
Padding the fabric is generally not used as a commercial technique because of the additional manufacturing processing costs. Since a liquid or lotion must be applied to the fabric anyway in a wet wiper product, and since the liquid or lotion without antimicrobial control or preservation agents represents a key opportunity for microbiological growth, the preferred method of applying the chemical preservation or antimicrobial control is to incorporate the soluble preservative agents in the lotion phase and then apply the preserved lotion to the fabric.
In either case, the end result is the same. Since the preservatives and antimicrobial agents are soluble in a liquid or lotion phase, they ultimately equilibrate throughout the wet wiper product and provide a homogenous chemical method of antimicrobial control. Unfortunately, when a wet wiper product of this type is ultimately used, the preservatives or antimicrobial agents remain behind on the user's skin from the liquid or lotion phase and leave an irritating residue on the skin. Many individuals exhibit adverse reactions to such preservatives, and hence, their enjoyable use of the wet wiper product is significantly impeded.
Moreover, both chemical solubility and antimicrobial spectrum activity considerations significantly limit the use of other, less harsh preservatives in the liquid wetting solution. Consequently, the present use of wet wiper products, such as those that use non-woven webs, has numerous inherent disadvantages.
Therefore, it would be desirable to incorporate the antimicrobial properties required in the wet wiper product in a manner substantive to and within the wet wiper fabric. In this manner, the issues of chemical solubility and antimicrobial activity considerations could be overcome because no harmful residue would be left on the skin of the user. In addition, the increased costs of padding the wet wiper fabric during its manufacturing process could be overcome by incorporating these substantive antimicrobials into the synthetic bonding agent typically already required for such non-woven fabrics.
In sum, present non-woven web products that exhibit antimicrobial activity are less than satisfactory. Often, the webs activity are less than satisfactory. Often, the webs contain preservatives that leave an irritating residue on the user's skin. Moreover, the use of various synthetic fibers and off-line treatment processes increase the cost of producing these non-woven web products.